> No, they aren't [corporations] legally or conceptually. Legally, they're in a unique class. They're 501c5s.
What do you think a 501(c)5 corporation is?
> Getting rid of them is the exact same process as starting one! You have to convince your coworkers and win a vote.
Sort of. Companies are strictly prohibited from taking retaliatory action against employees who attempt to organize their workplace. In extreme cases, this can even result in mandatory recognition of a union without a vote.
Unions, on the other hand, have great leeway to terminate membership association with members who speak out publicly against the union, which is de facto termination. They are also legally permitted to suppress counter-organizational activities in many other ways which companies cannot do legally to prevent the formation of a union.
In practice, deunionizing a workplace is many orders of magnitude more difficult than unionizing it, because you have to obtain the written permission of 30% of the bargaining unit without attracting the attention of the union leadership.
There's a reason that only 10% of union members in the US ever had the opportunity to vote (for or against) union representation - unions are not legally required to undergo periodic re-certification votes, and they are given great latitude to prevent themselves from ever having to face a vote.